1. Field of the Invention
The present invention relates generally to an electronic testing apparatus, and more specifically, to such an apparatus wherein one or more test probes are used to facilitate testing of a unit under test (UUT) that includes a ball grid array (BGA) device.
2. Brief Description of Related Prior Art
Many conventional automated systems/procedures currently exist for stimulus/response testing of various UUTs. In general, automated testing involves supplying test input stimuli (e.g., commands, data, etc.) to the UUT, observing actual outputs (e.g., actions, data, etc.) generated by the UUT in response to the stimuli, and comparing the actual outputs to outputs that are expected if the UUT is functioning properly. Depending upon the degree to which the actual outputs match those that are expected, the testing system will indicate either that the UUT has passed the test (i.e., is functioning properly), or has failed the test (i.e., is not functioning properly).
The printed circuit board (PCB) is one type of UUT for which many conventional automated systems/procedures/schema have been developed. A PCB may contain many different types of electrical components, at least some of which components may be surfaced mounted to the PCB. One of the more recently developed types of electrical components that may be surface mounted to a PCB is the BGA device.
The on-going trend in the industry toward miniaturization of electronic components has led increasingly to PCB surfaces becoming crowded with many closely-spaced electronic components. This has made testing of PCBs difficult, since it may be difficult to make electrical connections between the individual electronic components of the PCB UUT and the test analyzer circuitry necessary to perform the testing of the PCB, without either damaging and/or shorting together the electronic components. This problem has been particularly exacerbated by the fact that mounted BGA devices do not have the conventional leads that other types of PCB electronic components may have.
One conventional technique for testing a BGA device mounted to a PCB may involve manually contacting the individual BGA vias themselves, or connectors soldered thereto, with electrical test input and output probes so as to permit electrical test input and output vectors to be applied to and received from, respectively, the BGA device, without either damaging the BGA device or other electronic components of the PCB, or shorting such components together. As can be readily appreciated, in practice, this conventional technique may be slow and tedious to carry out, and may involve a substantial risk of introducing human error into the testing process. Additionally, the soldering of connectors to the BGA vias may render the PCB unsuitable, from a practical standpoint, for further use, after testing has been completed.
Accordingly, in broad concept, an apparatus is provided according to the present invention that overcomes the aforesaid and other disadvantages and drawbacks of the prior art. In one embodiment of the present invention, an apparatus is provided for use in testing a UUT. The UUT includes a BGA device that is physically connected to a first surface of a first PCB. The PCB also includes one or more vias on a second surface of the PCB. The first and second surfaces of the PCB face mutually opposite directions. The one or more vias are electrically connected to one or more electrically active points of the BGA device.
The apparatus of this embodiment includes first and second assemblies. The first assembly includes a multiplicity of members that extend from a surface of the first assembly. The first assembly also includes one or more electrically conductive test probes that extend from the surface of the first assembly. The second assembly includes openings that are dimensioned to receive respective members, and first and second mechanisms. When the members are in the openings, the first mechanism may engage the members. When the members are engaged by the first mechanism, the second mechanism may apply a force to the members that may cause the first assembly to be urged toward the second assembly. When the apparatus is in use testing the UUT, the members may extend through respective openings around the BGA device and the force applied by the second mechanism may permit the one or more test probes to be brought into physical and electrical contact with the one or more PCB vias. The respective openings in the PCB may be in a region of the PCB that extends around the periphery of the BGA device. The region may be devoid of active electronic components of the UUT.
In this embodiment, the apparatus may also include one or more stops that extend from the surface of the first assembly. The stops may be dimensioned to provide a gap between the second surface of the PCB and the surface of the first assembly when the apparatus is in use. The gap may be dimensioned to prevent the apparatus from damaging the UUT, but to allow the one or more test probes to contact the one or more vias when the apparatus is in use.
Alternatively, the members may each comprise two respective portions. One of these respective portions may be undersized relative to the respective openings in the PCB, and the other of these respective portions may be oversized relative to the respective openings in the PCB. When the apparatus is in use testing the UUT, the other of the respective portions may extend from the surface of the first assembly to the second surface of the PCB and may provide a gap between the second surface of the PCB and the surface of the first assembly that prevents the apparatus from damaging the UUT, but allows the one or more test probes to contact the one or more vias.
The one or more vias may comprise a plurality of vias. The one or more probes may comprise a plurality of probes, and the plurality of probes may contact respective vias. The apparatus may be dimensioned to contact the PCB, when the apparatus is in use testing the UUT, only at the respective vias and within regions of the PCB that are devoid of active electronic components.
The one or more test probes may be spring-loaded xe2x80x9cpogoxe2x80x9d pins. Also, the first assembly may comprise a second PCB and the surface of the first assembly may be a surface of the second PCB. The second PBC may include an electromechanical connection mechanism that may be used to electrically couple the one or more test probes to an electronic test analysis system.
By using the present invention, electrical test connections may be made between test circuitry and a BGA device mounted to a PCB UUT without having to manually contact the individual BGA vias or connectors soldered thereto, and without damaging the BGA device or other electronic components of the PCB, or shorting such components together. Thus, advantageously, by using the present invention, such electrical test connections may be made more easily, faster, and with less risk of introducing human error into the testing process, than may be possible according to the prior art.